The present invention relates to an airbag apparatus for protecting an occupant in a vehicle in case of a side collision, a roll over, and the like. More specifically, the present invention relates to an airbag apparatus having an airbag with an interior divided into a plurality of chambers.
An airbag apparatus for a side collision is known in which an airbag is deployed at a side of an occupant by a gas inflator, so that the deployed airbag receives the occupant.
Japanese Patent Publication (Kokai) No. 2000-177527 has disclosed a configuration in which a lower portion of an airbag is deployed with an internal pressure higher than that of an upper portion for receiving a lumbar region, or a middle part, of the occupant.
FIG. 15 is a side view of a seat having the airbag apparatus for a side collision disclosed in Japanese Patent Publication (Kokai) No. 2000-177527, and FIG. 16 is an enlarged cross sectional view of a portion 16 in FIG. 15.
An airbag 18 is divided into an upper chamber 20 and a lower chamber 22 by a seam 24. A rear end of the seam 24 is slightly away from a rear edge of the airbag 18, and a cylindrical tubular housing 30 is arranged at a gap or space between the rear end of the seam 24 and the rear edge of the airbag 18. A rod-shaped gas generator 36 is disposed in the tubular housing 30. Upper and lower ends of the tubular housing 30 are provided with pipe clips 32 and 34, so that the gas generator 36 is fixed with the pipe clips 32 and 34. The pipe clips 32 and 34 seal between the gas generator 36 and the tubular housing 30. The pipe clips 32 and 34 are attached to mounting positions 26 on a seatback 14.
The tubular housing 30 is provided with outlet ports 42 for the upper chamber for allowing gas to flow from the gas generator 36 into the upper chamber 20 and outlet ports 44 for the lower chamber for allowing gas to flow into the lower chamber 22. An opening area of the outlet ports 44 for the lower chamber is larger than an opening area of the outlet ports 42 for the upper chamber. Therefore, when the gas generator 36 is activated, the airbag 18 is inflated with an internal pressure of about 0.5 bar for the upper chamber 20 and an internal pressure of about 1.5 bar for the lower chamber 22.
In the airbag apparatus for a side collision disclosed in Japanese Patent Publication (Kokai) No. 2000-177527, the tubular housing 30 is used. Therefore, when the lower chamber 22 of the deployed airbag 18 receives the occupant, the gas in the lower chamber 22 flows through the tubular housing 30 into the upper chamber 20. Therefore, it is difficult to maintain the gas pressure in the lower chamber for a long time. Further, in the airbag apparatus for a side collision disclosed in Japanese Patent Publication (Kokai) No. 2000-177527, a space is formed between the rear end of the seam 24 and the rear edge of the gas distributor 30. Accordingly, the gas leaks from the lower chamber 22 with a higher inner pressure to the upper chamber 20 with a lower inner pressure. Therefore, the gas pressure of the lower chamber 22 decreases relatively quickly.
In view of the problems described above, the present invention has been made, and an object of the present invention is to provide an airbag apparatus in which a gas pressure in a lower chamber is maintained at a high pressure for a sufficiently long time.
Further objects and advantages of the invention will be apparent from the following description of the invention.